The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context. Cyclic shift (CS) separation is to be used as the primary multiplexing scheme of demodulation reference signals (DMRS) in LTE-advanced. OCC (orthogonal cover code) is one option to be used as a complementary multiplexing scheme for CS separation. Another option is to use IFDMA (interleaved frequency domain multiple access) as a complementary multiplexing scheme for CS separation.